__block_write

函数名称：__block_write_begin

函数原型：int __block_write_begin(struct page *page, loff_t pos, unsigned len, get_block_t *get_block)

返回类型：int

参数：

**调用者**
名称	描述
block_write_begin	lock_write_begin takes care of the basic task of block allocation and* bringing partial write blocks uptodate first.* The filesystem needs to handle block truncation upon failure.
block_page_mkwrite	lock_page_mkwrite() is not allowed to change the file size as it gets* called from a page fault handler when a page is first dirtied
nobh_write_begin	On entry, the page is fully not uptodate.* On exit the page is fully uptodate in the areas outside (from,to)* The filesystem needs to handle block truncation upon failure.

函数逻辑报告